Fluid Mechanics

Previous Projects in Fluid Mechanics

Particle Dynamics

The micro-syringes were developed with the goal of delivering a lyopholized drug just under the skin. However, even though the drug particles may be small, they may clog up the orifices as shown in the right two images. The left image shows a sudden contraction with some particles stuck to the edges showing the scale (40:1) of the orifice size to particle diameter. The right shows a particle cap formed by the particle sticking together (or flocculating). Boris Stoeber studied this phenomena as part of his PhD thesis work.

Flow interaction with DNA molecules

The images on the right show the conformational changes of DNA molecules as they pass through a micro-check valve. In section A, the DNA is completely stretched out due to the flow acceleration going into the check valve. The molecules start to recoil in the slower regions like at B. The DNA then restretches as the flow enters the channel F.

We are studying DNA-laden flows in order to improve our ability to design microfluidic systems. In addition, the ability to stretch out DNA molecules using fluid forces may make it possible to 'bar-code' the molecules for rapid identification. This work is being done in collaboration with Prof. Susan Muller in ChemE. The data was taken by Polly Shrewbury and the work was continued by Shelly Gulati.

Blood separation using functionalized post arrays

This research was done by Wes Chang who used Selectin coated post arrays to separate white blood cells. The inflammation cascade causes the cells to stick and roll on the posts. The membrane characteristics of the cells determine the rate at which they move down the array. The cells barely visible in the upper image are HL-60 myeloid cells. They can be concentrated up by up to 2 orders of magnitude as well as separated from other cell lines.

The bottom image are results from DPIV data taken of the flow field around the rectangular grid.